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package oracle.toplink.essentials.internal.indirection;

import java.util.*;
import oracle.toplink.essentials.queryframework.*;
import oracle.toplink.essentials.indirection.*;
import oracle.toplink.essentials.exceptions.*;
import oracle.toplink.essentials.internal.descriptors.*;
import oracle.toplink.essentials.internal.helper.*;
import oracle.toplink.essentials.internal.sessions.AbstractRecord;
import oracle.toplink.essentials.internal.sessions.UnitOfWorkImpl;
import oracle.toplink.essentials.internal.sessions.AbstractSession;

/**
 * 

Purpose

: * BasicIndirectionPolicy implements the behavior necessary for a * a ForeignReferenceMapping (or TransformationMapping) to * use ValueHolders to delay the reading of objects from the database * until they are actually needed. * * @see ForeignReferenceMapping * @author Mike Norman * @since TOPLink/Java 2.5 */ public class BasicIndirectionPolicy extends IndirectionPolicy { /** * INTERNAL: * Construct a new indirection policy. */ public BasicIndirectionPolicy() { super(); } /** * INTERNAL: * Return a backup clone of the attribute. */ public Object backupCloneAttribute(Object attributeValue, Object clone, Object backup, UnitOfWorkImpl unitOfWork) { //no need to check if the attribute is a valueholder because closeAttribute // should always be called first ValueHolderInterface valueHolder = (ValueHolderInterface)attributeValue;// cast the value ValueHolder result = new ValueHolder(); // delay instantiation until absolutely necessary if ((!(valueHolder instanceof UnitOfWorkValueHolder)) || valueHolder.isInstantiated()) { result.setValue(super.backupCloneAttribute(valueHolder.getValue(), clone, backup, unitOfWork)); } else { ((UnitOfWorkValueHolder)valueHolder).setBackupValueHolder(result); } return result; } /** * INTERNAL: * Return a clone of the attribute. * @param buildDirectlyFromRow indicates that we are building the clone * directly from a row as opposed to building the original from the * row, putting it in the shared cache, and then cloning the original. */ public Object cloneAttribute(Object attributeValue, Object original, Object clone, UnitOfWorkImpl unitOfWork, boolean buildDirectlyFromRow) { ValueHolderInterface valueHolder = (ValueHolderInterface) attributeValue; ValueHolderInterface result; if (!buildDirectlyFromRow && unitOfWork.isOriginalNewObject(original)) { // CR#3156435 Throw a meaningful exception if a serialized/dead value holder is detected. // This can occur if an existing serialized object is attempt to be registered as new. if ((valueHolder instanceof DatabaseValueHolder) && (! ((DatabaseValueHolder) valueHolder).isInstantiated()) && (((DatabaseValueHolder) valueHolder).getSession() == null) && (! ((DatabaseValueHolder) valueHolder).isSerializedRemoteUnitOfWorkValueHolder())) { throw DescriptorException.attemptToRegisterDeadIndirection(original, getMapping()); } if (this.getMapping().getRelationshipPartner() == null) { result = new ValueHolder(); result.setValue(this.getMapping().buildCloneForPartObject(valueHolder.getValue(), original, clone, unitOfWork, false)); } else { //if I have a relationsip partner trigger the indiretion so that the value will be inserted // because of this call the entire tree should be recursively cloned AbstractRecord row = null; if (valueHolder instanceof DatabaseValueHolder) { row = ((DatabaseValueHolder)valueHolder).getRow(); } result = this.getMapping().createUnitOfWorkValueHolder(valueHolder, original, clone, row, unitOfWork, buildDirectlyFromRow); Object newObject = this.getMapping().buildCloneForPartObject(valueHolder.getValue(), original, clone, unitOfWork, false); ((UnitOfWorkValueHolder)result).privilegedSetValue(newObject); ((UnitOfWorkValueHolder)result).setInstantiated(); } } else { AbstractRecord row = null; if (valueHolder instanceof DatabaseValueHolder) { row = ((DatabaseValueHolder)valueHolder).getRow(); } result = this.getMapping().createUnitOfWorkValueHolder(valueHolder, original, clone, row, unitOfWork, buildDirectlyFromRow); } return result; } /** * INTERNAL: * Return the primary key for the reference object (i.e. the object * object referenced by domainObject and specified by mapping). * This key will be used by a RemoteValueHolder. */ public Vector extractPrimaryKeyForReferenceObject(Object referenceObject, AbstractSession session) { if (this.objectIsInstantiated(referenceObject)) { return super.extractPrimaryKeyForReferenceObject(((ValueHolderInterface)referenceObject).getValue(), session); } else { return this.getOneToOneMapping().extractPrimaryKeysForReferenceObjectFromRow(this.extractReferenceRow(referenceObject)); } } /** * INTERNAL: * Return the reference row for the reference object. * This allows the new row to be built without instantiating * the reference object. * Return null if the object has already been instantiated. */ public AbstractRecord extractReferenceRow(Object referenceObject) { if (this.objectIsInstantiated(referenceObject)) { return null; } else { return ((DatabaseValueHolder)referenceObject).getRow(); } } /** * INTERNAL: * Return the original indirection object for a unit of work indirection object. * This is used when building a new object from the unit of work when the original fell out of the cache. */ public Object getOriginalIndirectionObject(Object unitOfWorkIndirectionObject, AbstractSession session) { if (unitOfWorkIndirectionObject instanceof UnitOfWorkValueHolder) { ValueHolderInterface valueHolder = ((UnitOfWorkValueHolder)unitOfWorkIndirectionObject).getWrappedValueHolder(); if ((valueHolder != null) && (valueHolder instanceof DatabaseValueHolder)) { ((DatabaseValueHolder)valueHolder).releaseWrappedValueHolder(); } return valueHolder; } else { return unitOfWorkIndirectionObject; } } /** * INTERNAL: * Return the "real" attribute value, as opposed to any wrapper. * This will trigger the wrapper to instantiate the value. */ public Object getRealAttributeValueFromObject(Object object, Object attribute) { // Changed for CR 4245. Use a static reference instead of .class if (ClassConstants.ValueHolderInterface_Class.isAssignableFrom(attribute.getClass())) { return ((ValueHolderInterface)attribute).getValue(); } else { return attribute; } } /** * INTERNAL: * Iterate over the specified attribute value, */ public void iterateOnAttributeValue(DescriptorIterator iterator, Object attributeValue) { iterator.iterateValueHolderForMapping((ValueHolderInterface)attributeValue, this.getMapping()); } /** * INTERNAL: * Return the null value of the appropriate attribute. That is, the * field from the database is NULL, return what should be * placed in the object's attribute as a result. * In this case, return an empty ValueHolder. */ public Object nullValueFromRow() { return new ValueHolder(); } /** * INTERNAL: * Return whether the specified object is instantiated. */ public boolean objectIsInstantiated(Object object) { return ((ValueHolderInterface)object).isInstantiated(); } /** * INTERNAL: * Set the value of the appropriate attribute of target to attributeValue. * In this case, place the value inside the target's ValueHolder. */ public void setRealAttributeValueInObject(Object target, Object attributeValue) { ValueHolderInterface holder = (ValueHolderInterface)this.getMapping().getAttributeValueFromObject(target); if (holder == null) { holder = new ValueHolder(attributeValue); } else { holder.setValue(attributeValue); } super.setRealAttributeValueInObject(target, holder); } /** * INTERNAL: * Return whether the type is appropriate for the indirection policy. * In this case, the attribute type MUST be ValueHolderInterface. */ protected boolean typeIsValid(Class attributeType) { return attributeType == ClassConstants.ValueHolderInterface_Class || attributeType == ClassConstants.WeavedAttributeValueHolderInterface_Class; } /** * INTERNAL: * Verify that the value of the attribute within an instantiated object * is of the appropriate type for the indirection policy. * In this case, the attribute must be non-null and it must be a * ValueHolderInterface. * If the value is null return a new indirection object to be used for the attribute. */ public Object validateAttributeOfInstantiatedObject(Object attributeValue) { // PERF: If the value is null, create a new value holder instance for the attribute value, // this allows for indirection attributes to not be instantiated in the constructor as they // are typically replaced when reading or cloning so is very inefficent to initialize. if (attributeValue == null) { return new ValueHolder(); } if (!(attributeValue instanceof ValueHolderInterface)) { throw DescriptorException.valueHolderInstantiationMismatch(attributeValue, this.getMapping()); } return attributeValue; } /** * INTERNAL: * Verify that attributeType is correct for the * indirection policy. If it is incorrect, add an exception to the * integrity checker. * In this case, the attribute type MUST be ValueHolderInterface. */ public void validateDeclaredAttributeType(Class attributeType, IntegrityChecker checker) throws DescriptorException { super.validateDeclaredAttributeType(attributeType, checker); if (!this.typeIsValid(attributeType)) { checker.handleError(DescriptorException.attributeAndMappingWithIndirectionMismatch(this.getMapping())); } } /** * INTERNAL: * Verify that getter returnType is correct for the * indirection policy. If it is incorrect, add an exception * to the integrity checker. * In this case, the return type MUST be ValueHolderInterface. */ public void validateGetMethodReturnType(Class returnType, IntegrityChecker checker) throws DescriptorException { super.validateGetMethodReturnType(returnType, checker); if (!this.typeIsValid(returnType)) { checker.handleError(DescriptorException.returnAndMappingWithIndirectionMismatch(this.getMapping())); } } /** * INTERNAL: * Verify that setter parameterType is correct for the * indirection policy. If it is incorrect, add an exception * to the integrity checker. * In this case, the parameter type MUST be ValueHolderInterface. */ public void validateSetMethodParameterType(Class parameterType, IntegrityChecker checker) throws DescriptorException { super.validateSetMethodParameterType(parameterType, checker); if (!this.typeIsValid(parameterType)) { checker.handleError(DescriptorException.parameterAndMappingWithIndirectionMismatch(this.getMapping())); } } /** * INTERNAL: * Return the value to be stored in the object's attribute. * This value is determined by the query. * In this case, wrap the query in a ValueHolder for later invocation. */ public Object valueFromQuery(ReadQuery query, AbstractRecord row, AbstractSession session) { return new QueryBasedValueHolder(query, row, session); } /** * INTERNAL: * Return the value to be stored in the object's attribute. * This value is determined by the row. * In this case, simply wrap the object in a ValueHolder. */ public Object valueFromRow(Object object) { return new ValueHolder(object); } }




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